


Distributive Property

by nitohkousuke



Category: Kamen Rider Build
Genre: M/M
Language: English
Status: Completed
Published: 2018-08-29
Updated: 2018-08-29
Packaged: 2019-07-03 23:25:30
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,261
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15829074
Author URL: https://archiveofourown.org/users/nitohkousuke/pseuds/nitohkousuke
Summary: Post- SeriesRyuuga and Sento figure out their place in this new world with eachother.





	Distributive Property

**Author's Note:**

  * For [kitarin](https://archiveofourown.org/users/kitarin/gifts).



> i rambled gomen ne

“How did you get money for this anyway?” Ryuuga says inspecting the money that Sento’s pulled out to count to make sure he has enough for both meals today as well as the room they’re staying at. The currency is still strange to him, but he’s grateful it’s still a standard number system. It’s different from the dollarks that he’s used to, and honestly, there’s far more coins than he’s used to carrying. At least the internet works exactly the same and he can keep researching whatever he needs.

 

“I’m a genius Physicist. I just open my mouth, and people just want to give me money, obviously.” Sento says without missing a beat, spacing out exactly how much he thinks they’ll need today. Ryuuga is predictable in his orders and Sento honestly can easily work himself within his financial budget...as long as he doesn’t get sidetracked and spend money on something unplanned like he has been today.

 

His eyes drift to the blue dragon plushie that’s practically sitting on the table as if it had a third place at the table set up for it. The flecks of gold shine as the light reflects off of it.

 

“ _Okay, we just need to buy some basic necessities. I only have enough for that.” Sento says as the step into the convenience store, trying to find the aisle they need. They’ve only been here a few days, but the hotel shampoo honestly isn’t his favorite scent. They need more to live off of for now at least before he can figure out where they can live._

 

_After all, this TV show will take forever to actually set up and get approved. Until then, they’re just going to have to make due._

 

“ _Yeah, yeah. I’ll make sure not to grab too much candy this time.” Ryuuga grumbles, a little cranky that Sento’s dragged them out a little earlier than usual. But there are a lot of different errands he wants to run before they can actually do what he wants to later._

 

“ _I’m not saying you can’t buy any!” Sento pouts back at him, grabbing some cans of coffee that he plans to buy._

 

_Ryuuga doesn’t say anything after that. Actually, he’s surprisingly quiet, which makes Sento worry. That’s how he tracks him down to a little display in the middle of the store with a set of small plushies on it. Sento follows Ryuuga’s gaze to the blue dragon on the top shelf._

 

“… _.I uh.” Ryuuga says quickly, looking away. “They’re cute and kind of dumb looking right?” But Sento can see the fondness he had for a moment._

 

_He doesn’t have the material to rebuild cross-z and really it’s a weapon he shouldn’t rebuild right now. Perhaps if he redesigned it to be less weaponized, but he also doesn’t have the time._

 

_So he takes the plushie off the display and walks towards check out with the rest of the items they need._

 

“ _Wait. Sento! Come on. That’s like 10 candy bars worth. There’s no way you can get that after all your whining.” Ryuuga walks after him, trying to gently take the plushie from him._

 

“ _Hm….I think my financial budgeting can make it work. After all, a genius like me is more than capable of juggling some numbers.” Sento says as he puts down one of his cans. That should be more than enough of a difference. “Besides, Cross-Z is part of the family. Are you telling me to not bring him along?” And Ryuuga blinks a few times staring at him when he says that, before a pink dusts his cheeks and he looks away._

_On the way out, Ryuuga punches his shoulder, after Sento hands the plushie off to him._

 

“ _I’m gonna buy you like 60 bunny plushies when I get a job you know.” He says with determination that Sento can’t help but laugh at a little. His heart flutters hard in his chest._

 

“ _60 bunnies? What am I going to do with them? Why 60?” Sento says quickly trying to process why that number sounds familiar._

 

“ _One...uh...for all the full bottles you know? I know you liked those things. Or I guess….I’d get you a fidget thing. I know you’d like shake those all the time.” Ryuuga mumbles, Sento thinks he’s probably realizing that maybe 60 bunny plushies is a ridiculous gesture. If he did buy that many, Sento would just cover the bed in them honestly. He’d cherish every single one of them._

 

“ _Hm...I do miss how they’d keep my hands busy…” Sento says looking off. The power those bottles had though was dangerous, and he feels guilty for how he misses their shape in his hands. He could easily make some fake. Maybe he will...but for now…_

 

“ _For now, I think I have more than enough to keep my hands busy.” Sento says, not able to look Ryuuga in the eyes as he slips his hand in his._

 

“Yeah to make you stop rambling for hours at them maybe.” Ryuuga teases, punching his shoulder. And there’s a pause like he’s actually thinking about what Sento’s been doing. “Have you been…?”

 

“I’ve been doing some work on the internet. A lot of freelance physics and mathematical and engineering. All completely legal.” He isn’t Katsuragi. Who’s name has actually come up several times in all the subjects that he’s enjoyed to work on. All on infrastructure and the good of humanity. “And once we have real papers, I can get a proper research grant once everyone sees how great I really am.”

 

“...Yeah. You’ll totally rock this world.” Ryuuga says leaning back in his seat. “Dunno what I’m gonna do though. Can’t do MMA because of the other me.” And Sento can hear something in his voice that makes his heart hurt briefly. Because the other him being there means he can’t see his parents. Any of his old friends. Or Kasumi.

 

“Well, obviously, you’re going to me my incredibly attractive lab assistant.” Sento tries to tease him but he can still feel some of the tension in the air. He’d suggest going to see a match or two, but he knows that would hurt more than it would do anything else. It’s why Sento’s avoided doing any work that involves his...Takumi’s father. Not that he hasn’t actually technically worked on something with Takumi at this point. But he’s sure his name means nothing to him. This world has traces of both worlds, not that he knows much about this world before everything, but he can feel it.

 

“You said I was too clumsy to be near your stuff half the time.” Ryuuga pouts at him as the waiter comes over and takes their order for exactly what Sento predicted. Ryuuga isn’t wrong. The amount of repairs he’s had to make due to a simple thing being dropped at the wrong place or time at this point is….astounding. But Sento enjoys his presence. So it’s worth it in the end.

 

“Hmmmm. You could teach martial arts to kids you know? Or do MMA at a lower level. I heard fake Banjou is at a ridiculously pro level. And honestly, thinking on it, he’s completely free of any alien influence and has a completely different upbringing. It’s likely that your fighting styles are different enough no one will notice.” Sento says already calculating the differences between the two of them based partially on their small interaction.

 

“Yeah but what if I had to fight him or something? I’d feel bad punching myself in the face.” Ryuuga leans back further and honestly Sento is thinking about telling him to stop leaning so far back. But Ryuuga’s sense of balance is light years above his own and he’s sure he has a better grasp at how to not fall back on those anyway.

 

“You wouldn’t want to punch yourself in the face? Fair, I suppose that’s a normal reaction.” Sento mumbles trying to hide the fact that he has punched Takumi in the mirror equivalent of a face a total of three times. But Sento knows it’s more about Kasumi than it is about any sort of self-esteem thing. But he’s not going to bring that up.

 

“Besides, we don’t have papers or let alone a place to call our own. I’ll worry about where to apply when I have something to actually write down on the application.” Ryuuga nods as he steals some of Sento’s Tamagoyaki off his plate. It’s not nearly as sweet as he likes, which is why Ryuuga can even stand it. Usually Sento would stop him, but honestly, Sento just takes some food off of his plate in response.

 

“You’re right. We can’t just live out of that hotel forever. Once, I get us our papers we can start looking for an apartment. I figured we didn’t want to leave this area.” There was still a possibility of people remembering. Even if maybe it was better they never did. Maybe it was selfish, but Sento didn’t want to leave them entirely. Besides, this area had a Phenomenal Physics department. He’d be a fool to not work here.

 

“How do you get papers anyway? Did you have fake papers in the last world too?” Ryuuga says through the last mouthful of food on his plate. “Because, you went to work back in Toutou right? You applied and everything. So you had to have some kind of documents and stuff?”

 

“…Evolt had connections to get my documents pretty easily. I might have found similar ones to get the same thing. Though, I’m going to change my birthday from the last one I think all things considered.” Sento mumbles looking away again. He’s thought a lot about this. About their papers. So much of what they know doesn’t exist. The places they were born in no longer exist. They’ll have to have fake parent names as well. So what’s a birthday on top of all of that.

 

There’s a pause before Ryuuga manages to catch his eyes again. “Did you...have a different birthday than...you know….Katsuragi’s? Cause like, your body was born that day right? But you wouldn’t have known that...” He can tell there’s a delicateness in his tone about the subject. He appreciates it, but he doesn’t need it.

 

Though, he does occasionally miss his connection with the other. As well as all the memories, he never actually shared with him. Though, he supposes, memories of the Devil’s scientist are better left unknown. He won’t need them for his show either. After all, he’s the star, not Katsuragi.

 

“It was the day he wiped my memories actually. I’d rather not celebrate that day after everything.” Because that wasn’t the day the real Sento was born anyway. At least not in his heart. “I’m going to change it to December 10th.” It’s a date that means a lot more to him.

 

There’s a shuffle as they stand up, Sento having just paid the bill exactly within the budget he set himself out to spend. Ryuuga picks up Cross-Z, placing him in his pocket so his head can just poke out of it. Which according to Ryuuga, Cross-Z is really fond of. He nearly blends into the jacket, that Sento is grateful they fond at a thrift store on their first day.

 

“….Really?” Ryuuga gives him a disbelieving look as Sento leads the way to the park, where they’ve been sitting out on a bench that has the perfect view on the top of the hill to discuss the layout of Kamen Rider Build.

 

And for a moment, Sento turns around and wonders if Ryuuga really does remember that day as well as he does because honestly he doesn’t at all and if it wasn’t for his perfectly dated notes, that are honestly an organizational disaster as much as he tried to keep up with his own system, he would have no idea that was the day.

 

“There’s no way you’re a Sagitarius." Ryuuga starts and Sento opens his mouth to retort why the basis of Horoscopes has absolutely no scientific backing, but if it did, he’d like to think he fits some of those requirements not that he’s looked into it at all. No why would he. But Ryuuga interrupts him before he can comment on that. “Isn’t that the day in the rain…?”

 

“Oh...so it is. I just thought it was a good day...” Sento starts, his own face dusted a darker shade of red than he’ll ever admit. “...A day I realized who I really was and what I was fighting for...”

 

Ryuuga bumps into him, his shoulder hitting hard against his. The grin on his face is blinding. “I was the hero that day wasn’t I? Saved you and all.” There’s a lot more to it than that, but neither of them want to talk about it past this. About what would have happened if Ryuuga hadn’t shown up. Evolt wouldn’t have killed him, but Sento would have let him. “Maybe we should name the show Kamen Rider Cross-Z, after all. How many times have I saved you?” Ryuuga shoves him again before pounding his fist on his chest.

 

Ryuuga has saved him more times than he can count. He’d make some kind of comment about infinity uncountable sets to talk about the sheer size, but he knows it’s something that would be lost on him. It doesn’t make it any less true.

 

“Sometimes, the supporting cast have their moments it’s true. But that doesn’t mean they usurp the true protagonist. After all, a good hero knows how to share the spot light with his secondary.” Sento pokes him in the chest before turning away to do his usual flourishing gesture. “Besides, we can give you a spin off movie or something.”

 

Sento takes the closeness as an opportunity to slip his hand in Ryuuga’s, falling in line with his pace as they stroll the path. The road is similar to one Sento’s walked several times in the past. One he used to walk sometimes at night when he was stuck and couldn’t properly pace in the lab. He can remember traces of formulas every time he walks down it. It’s weird to not have the sky wall in the view, but Sento’s grateful for it. Grateful for all of this despite how strange it is sometimes.

 

“Just a spin off movie.” Ryuuga pouts leaning into him. Sento can help but laugh fondly at him.

 

“It’ll be a good one. Maybe I’ll even write myself as your love interest. You can save me, princess style and all. Oh Banjou, my hero, save me.” Sento raises his other hand against his head in an over dramatic gesture as he raises his voice a little higher.

“You really gonna call me Banjou still during that? After everything?” Sento knows the question isn’t just about the movies or the show. It’s about the fact that Sento after everything still for the most part calls him by his family name when they’re in public. At least, he calls him Ryuuga in the privacy of their own home. But Sento knows that there’s something about it that probably bugs him. Just like when Sento uses a tad too much sarcasm when they’re talking about feelings and Ryuuga’s actually trying to be serious. Sento’s not too good at feelings sometimes. It’s not like Ryuuga’s all that much better.

 

They're both kind of disasters.

 

“Hmm, I suppose you’re right. I’ll have to see when this movie takes place. After all, maybe I’ll write something post series. After the new world and everything. Though, that will indeed be entirely fiction.” Sento starts, grateful for a topic that perfectly Segways into something he’s needed to talk about right now.

 

“You know what I mean, Sento.” Ryuuga gives him a look as they’ve reached the bench they’ve been talking on. “I’ve been calling you Sento since like..” He trails off as he tries to remember when that started. It doesn’t feel like he’s been called Sento for forever.

 

“Since, you stopped me from being an idiot in the Faust hide out. Though, I remind you, that was after you knocked me unconscious and tried to sneak into the hideout yourself using a civilian you turned back into a smash.” Poking him in the chest again, Sento crosses his arms and looks away, trying to keep a teasing tone in his voice as he talks. “Which is another reason why the show is called Kamen Rider Build.”

 

“How do you even remember that so perfectly? That was like…..Episode…...10? I’m the kind of hero that had a whole arc about becoming as awesome as I am!” Ryuuga walks in front of him, crossing his own arms as he locked his gaze with Sento.

 

“I’ve been writing down notes since the day I met you.” Oh that’s embarrassing to admit. That Ryuuga was what caused him to even think about writing down things about his past to the extent that he did. It was simply that it was the first lead that he’d ever had on the matter. “Also, it’s episode 6.” They’re moving away from the subject he really wants to talk about.

 

“Not all of us are as straight forward as you are-”

 

“Well, I mean I’m not as straight as I used to be I think now.” Ryuuga grins, giving him a look that Sento immediately frowns and looks away his ears turning bright red.

 

“I was never straight.” Sento immediately retorts. “But that’s besides the point.” This is so much harder than it’s supposed to be. He’d had 15 different plans for this, and all of them have now been ruined.

 

“Do you mean like you or like-”

 

“I’m not going to discuss Katsuragi’s love life, not that he let me have access to any of those memories.” It’s for the best. “I don’t think you want to hear that either.” In the end, Katsuragi had given him his blessing, begrudgingly, with Ryuuga, but he never let him hear the end of how apparently terrible his tastes in men where. It wasn’t like he had any right considering Gentoku’s choice in clothing most of the time.

“Besides, Ryuuga.” Sento starts, and it’s private enough of a place that calling him by his given name doesn’t really hold the weight he wants it to. It gets his attention enough though. “It was just a matter of...” Of what? Of not wanting to get too close too fast? Of not wanting to admit his feelings too fast? It was too late for any of that. Because they both knew how fast they’d fallen for each other. From the first day they made out in the bed to every single time they’d sacrificed themselves for the other back and forth.

 

“Well, it doesn’t matter now.” Sento starts looking away again, the red spreading from his ears to his cheeks. Because it was a matter of the fact that he didn’t deserve Ryuuga. He’d realized that fast. Because after everything, he’d caused so much damage both willing and accidentally. Even this merge of worlds didn’t leave him without so blood on his hands that he could hardly believe he was allowed to have all of this with him now. For them to be able to live in a world without war together. But he knew if he said any of that out loud, Ryuuga would probably be really mad that he was putting himself down like that. And also, the ego that he had prevented him from saying things like that out loud in moments like this.

 

Ryuuga opens his mouth to retort because the way Sento says that is so callous. He knows sometimes he talks like that and it seems like he doesn’t care especially when his anxiety is clawing itself out of him like it is at this point.

 

“Because, that’s not going to be your family name anymore honestly. You can’t go by Banjou Ryuuga with the face that you have even if your hair is a much better color than Fake Banjou. So you’re going to have to change your name.” This is not how he wanted this to go at all. They were at a nice park. It was a beautiful day. Sento had bought Ryuuga a lovely plushie. Sure he didn’t have enough money for anything else, but surely for one moment, his brain and his mouth could work together and not be a total disaster.

 

“What? No way dude. Just because that weird black hair me has my name and he’s famous because he didn’t have to throw his fights doesn’t mean I should give up my name. I like my name!” Ryuuga looks genuinely distressed at this. Which is fair. Sento could almost relate if his name wasn’t a gift from a man who practically named his shiny gun, gun. But it was a name that was built by his friends more than anything else, and for that he’d hate to change it.

 

“Don’t worry. I’ve got a fantastic name for you. You’ll love it.” Sento wanted to lean in close. To really make this moment as good as it needs to be. But he’s too nervous. As great and amazing as he is, he’s far too nervous to even remotely fake any confidence here. Not that he needs to fake confidence, he knows he has this in the bag. He’s thought of a thousand ways this could go and almost all of them end positively. So why does he feel so nervous that his throat has gone dry.

 

“You can’t just pick a name without asking me. I gotta write it down on stuff. Look at it forever. I should have some say in that.” Ryuuga retorts, shoving him lightly.

 

“I was going to ask for your approval. Though, I’m sure Kiryuu Ryuuga is a name you’d have no issue with.” The words come out of his mouth so fast he wonders if maybe Ryuuga doesn’t hear them. Because he’s quiet for awhile. And Sento wonders if he can just say something else and they can pretend he never said anything at all. His face grows hot in embarrassment, and he wonders if he’s managed to make the one person who knows anything about him anymore upset. Because he knows what kind of weight what he’s just said holds. Because he knows what this means. Because he knows in a world where their friends don’t remember them and honestly might never that this hurts.

And just as Sento is about to open his mouth to try and take it back, eyes almost hot with tears, Ryuuga grabs him by the collar and smashes their lips together. Sento blinks for a few moments and almost doesn’t respond. But he catches himself quickly and kisses back hard, moving one hand to Ryuuga’s Waist to pull him closer. The kiss is harder and more frantic than any of their kisses recently besides the first one in the hotel on their first day back, and Sento doesn’t want to break it until of course he absolutely can’t. Ryuuga pulls away and Sento can see the way he’s just barely bruised his lips. His lip are probably worse.

 

“Ask properly. You don’t have to like get a ring right now because I know we definitely don’t currently have the money. But you can at least ask properly.” The slight blush on his cheeks with the pout on his face makes Sento’s heart soar.

 

“Banjou Ryuuga, will you marry me, the fantastic, wonderful genius physicist, Kiryuu Sento-” Sento starts drawing out all the compliments about himself.

 

“That’s not what I mean. Come on dude.” Ryuuga rolls his eyes at him.

 

“Nope that’s all you get.” Sento’s too nervous to do that anymore seriously. He’s already dizzy on excitement and nerves and the buzzing feeling of his lips.

 

“Senttoooooo. This is something you could maybe be a little more honest on.” Sento is honest. Sometimes. He can be. It’s hard. Feelings are hard. He has no idea how Ryuuga is so straight forward. It takes Sento thousands of words to just get a simple idea across.

 

“I love you, Ryuuga.” Sento blurts out, completely and utterly seriously. It’s not the first time he’s said it, but he’s not one to say it often. It holds more weight than he’s willing to admit. He’s only said it in the private in moments where it’s mattered. Not that this isn’t a moment that matters, but it’s not exactly private.

 

“I love you too, Sento.” Ryuuga leans forward, to kiss him again, softer this time. Sento’s heart swells when he hears him say it. Not that he doesn’t know that it’s true at this point, but it’s...always nice to hear.

 

They take a moment to just stand there in the summer air that’s almost fall before sitting back down at the bench. Sento takes out all the notes they’ve had before he pauses.

 

“That’s….that’s a yes right?”

 

“Of course that’s a yes. I thought you were a genius.” Ryuuga teases, knocking his shoulder into his.

 

“I just wanted to hear you say it.” Sento pouts. “Though we’ll have to give you some random name as a maiden name obviously.”

 

But that’s a simple matter. Something they can work on together. Like they have been for the past year. Like they can in the future.

 

After all, they’re a best match.


End file.
